1. Field of the Invention
The present invention relates to a method for adhering a member and an apparatus for adhering a member to a base; especially a method for adhering a thin member and an apparatus for adhering a thin member to a base with a high degree of precision.
2. Description of the Related Art
For example, a process to manufacture magnetic heads includes a process to adhere a thin film magnetic head to a work piece. In the adhesion of these thin film magnetic heads, a high precision positioning and a uniform adhesive strength are necessary in order for a subsequent lapping. However, the thin film magnetic head is affected by the adhesive because it is very thin and it is difficult to satisfy such requirements.
Consequently, technology to adhere a member to a base with a high degree of precision and with good adhesive strength is required.
FIG. 25A and FIG. 25B are figures to explain composite magnetic heads.
As shown in FIG. 25A, the composite magnetic heads comprise a write element 85 and a magnetoresistive element 82 formed on a substrate 81. The magnetoresistive element 82, as shown in FIG. 25B, comprises a magnetoresistive film 83 and a pair of conducting films 84. The magnetoresistive element 82 is an element for which the value of resistance changes due to an external magnetic field. The magnetoresistive element 82 is a read element to output current of a size corresponding to the magnetic force of a track 90 of a magnetic disk.
Because the magnetoresistive element 82 is an element which can only read, it must have a write element installed separately. The write element 85 is constituted of an inductive head. The write element 85 comprises a lower magnetic pole 86 and an upper magnetic pole 88 which faces the lower magnetic pole 86 across a gap. A coil 87 to excite these magnetic poles 86 and 88 is installed between these magnetic poles 86 and 88. A non-magnetic insulating layer 89 is installed around the periphery of the coil 87.
In such a composite magnetic head, the value of resistance of the magnetoresistive film 83 of the magnetoresistive element 82 must be constant in each head. However, it is difficult to produce the films with a constant value of resistance in the process for manufacturing the thin film of the magnetic heads. For this reason, after forming the thin film of the magnetic heads, the height (amplitude) h of the magnetoresistive film 83 is finished to a constant value and the values of resistance are made constant.
FIGS. 26A, 26B, 26C, 27A, 27B, 27C and 27D are figures to explain the manufacturing process for such composite magnetic heads.
As shown in FIG. 26A, a plurality of composite magnetic heads 101 are formed on a wafer 100 with thin film technology. Next, as shown in FIG. 26B, the wafer 100 is cut and a row-bar 101 is prepared. This row-bar 101 comprises one row of magnetic heads 102.
The magnetic heads 102 undergo lapping at a constant height of the magnetoresistive film 83, as discussed above. However, the row-bar 101 is very thin, for example it is 0.3 millimeters. For this reason, it is difficult to mount it directly on the lapping jig. For this reason, as shown in FIG. 26C, the row-bar 101 is adhered on a mounting jig (base) 103 with heat-melting wax.
Then, as shown in FIG. 27A, the row-bar 101 is placed on the lap surface plate 104 and undergoes lapping. The height of the magnetoresistive film 83 is thereby made constant. Then, as shown in FIG. 27B, a slider is formed on the lower surface 101-1 of the row-bar 101.
Then, as shown in FIG. 27C, the row-bar 101 is cut into individual magnetic heads 102 while still mounted on the mounting jig 103. Then, as shown in FIG. 27D, the individual magnetic heads 102 are released while the mounting jig 103 is heated and the heat-melting wax is melted.
In this way, a row-bar 101 comprising a row of magnetic heads 102 is prepared and a plurality of magnetoresistive film of magnetic heads 102 can undergo lapping at one time because lapping is applied at the level of the row-bar 101.
Because lapping is applied at the level of the row-bar 101 comprising a plurality of magnetic heads, the row-bar 101 must be adhered with good precision to the mounting jig 103. In other words, the precision in micron units for positioning and lapping with respect to the mounting jig 103 is required.
FIG. 28A and FIG. 28B are diagrams to explain the prior art.
Conventionally, a row-bar 101 is mounted on and adhered to a heated mounting jig 103 after heated heat-melting wax is applied by hand.
Meanwhile, a mechanism for applying adhesive is also known. As shown in FIG. 28A, dots of adhesive 105 are applied automatically on a base 103 with an application mechanism. Then the member 101 is placed thereon.
Also, as shown in FIG. 28B, lines of adhesive 106 are automatically applied on a base 103 with the application mechanism moving from the starting end to the finishing end of the base 103. Then the member 101 is placed thereon.
However, the member conforms to the adhesive in the case of adhering a very thin member, of 1 mm or less, such as the row-bar. For this reason, in the conventional, manual method, the problems are that there are non-uniformity of the thickness of the adhesive layer, great warping of the member, and non-uniformity of the adhesive strength.
Also, in the method with an application mechanism to effect spot application, the problems are that there are great warping of the member and non-uniformity of adhesive strength due to the non-uniformity of the thickness of the adhesive layer because of the dots of adhesive.
Furthermore, in the method with an application mechanism to effect line application, non-uniformities in the adhesive layer occur easily at the starting and ending points on the base 103 as shown in FIG. 28B. For this reason, the problems are great warping of the member and non-uniformity of adhesive strength.
Moreover, there are problems of the member conforming to the adhesive, warping of the member, and low precision of positioning because the member is simply placed on the base 103 on which adhesive was applied.